Methods and apparatus for position location in a wireless network

Abstract

Methods and apparatus for position location in a wireless network. In an aspect, a method is provided that includes determining whether a symbol to be transmitted is an active symbol, wherein the symbol comprises a plurality of subcarriers, and encoding identification information on a first portion of subcarriers if it is determined that the symbol is the active symbol. The method also includes encoding idle information on a second portion of subcarriers if it is determined that the symbol in not the active symbol. In an aspect, an apparatus includes detector logic configured to decode a plurality of symbols to determine identification information that identifies a plurality of transmitters, and to determine a plurality of channel estimate associated with the plurality of transmitters. The apparatus also includes position determination logic configured to calculate a device position based on the plurality of transmitters and the plurality of channel estimates.

What is claimed is: 
     
       1. A method for determining a position of a device in a network, the method comprising:
 decoding a symbol comprising subcarriers to determine identification information that identifies a transmitter, the decoding comprising partitioning the subcarriers of the symbol; 
 determining a channel estimate associated with the transmitter; 
 repeating the decoding and the determining for a plurality of symbols so that a plurality of transmitters associated with a plurality of channel estimates, respectively, are determined; and 
 obtaining the position of the device based at least in part on positions of the plurality of transmitters. 
 
     
     
       2. The method of  claim 1 , in which calculations for obtaining the position are performed at a server or the device. 
     
     
       3. The method of  claim 1 , in which obtaining the position comprises using triangulation. 
     
     
       4. The method of  claim 1 , in which determining the position comprises accounting for fixed offsets applied by the plurality of transmitters. 
     
     
       5. The method of  claim 1 , in which the symbol is a positioning pilot symbol. 
     
     
       6. The method of  claim 5 , in which the positioning pilot symbol includes an increased cyclic prefix. 
     
     
       7. The method of  claim 1 , in which the partitioning comprises partitioning the subcarriers of the symbol into a plurality of interlaces. 
     
     
       8. The method of  claim 7 , in which the decoding further comprises decoding the plurality of interlaces to determine a wide area scrambler seed (WID) value or a local area scrambler seed (LID) value. 
     
     
       9. The method of  claim 1 , in which determining the channel estimate comprises determining a transmission time associated with the transmitter. 
     
     
       10. The method of  claim 1 , in which the symbol comprises an Orthogonal Frequency Division Multiplexing (OFDM) symbol. 
     
     
       11. An apparatus for determining a position of a device in a network, the apparatus comprising:
 means for decoding a symbol comprising subcarriers to determine identification information that identifies a transmitter, the means for decoding comprising means for partitioning the subcarriers of the symbol; 
 means for determining a channel estimate associated with the transmitter; 
 means for repeating the decoding and the determining for a plurality of symbols so that a plurality of transmitters associated with a plurality of channel estimates, respectively, are determined; and 
 means for obtaining the position of the device based at least in part on positions of the plurality of transmitters. 
 
     
     
       12. The apparatus of  claim 11 , further comprising means for providing information to a server for calculating a device position based at least in part on the plurality of transmitters and the plurality of channel estimates. 
     
     
       13. The apparatus of  claim 11 , in which the means for obtaining the device position comprises means for using triangulation. 
     
     
       14. The apparatus of  claim 11 , in which the means for obtaining the device position comprises means for accounting for fixed offsets applied by the plurality of transmitters. 
     
     
       15. The apparatus of  claim 11 , in which the symbol is a positioning pilot symbol. 
     
     
       16. The apparatus of  claim 15 , in which the positioning pilot symbol includes an increased cyclic prefix. 
     
     
       17. The apparatus of  claim 11 , in which the means for partitioning comprises means for partitioning the subcarriers of the symbol into a plurality of interlaces. 
     
     
       18. The apparatus of  claim 17 , in which the means for decoding comprises means for decoding the plurality of interlaces to determine one of a wide area scrambler seed (WID) value or a local area scrambler seed (LID) value. 
     
     
       19. The apparatus of  claim 11 , in which the means for determining comprises means for determining a transmission time associated with the transmitter. 
     
     
       20. The apparatus of  claim 11 , in which the symbol comprises an Orthogonal Frequency Division Multiplexing (OFDM) symbol. 
     
     
       21. A computer program product for determining a position of a device in a network, the computer program product comprising:
 a non-transitory computer-readable medium having program code recorded thereon, the program code comprising:
 program code to decode a symbol comprising subcarriers to determine identification information that identifies a transmitter, the program code to decode comprising program code to partition the subcarriers of the symbol; 
 program code to determine a channel estimate associated with the transmitter; 
 program code to repeat the decoding and the determining for a plurality of symbols so that a plurality of transmitters associated with a plurality of channel estimates, respectively, are determined; and 
 program code to obtain the position of the device based at least in part on positions of the plurality of transmitters. 
 
 
     
     
       22. The computer program product of  claim 21 , in which calculations to obtain the position are performed at a server or the device. 
     
     
       23. The computer program product of  claim 21 , in which the program code to obtain the position comprises program code to use triangulation. 
     
     
       24. The computer program product of  claim 21 , in which the program code to obtain the position comprises program code to account for fixed offsets applied by the plurality of transmitters. 
     
     
       25. The computer program product of  claim 21 , in which the symbol is a positioning pilot symbol. 
     
     
       26. The computer program product of  claim 25 , in which the positioning pilot symbol includes an increased cyclic prefix. 
     
     
       27. The computer program product of  claim 21 , in which the program code to partition comprises program code to partition the subcarriers of the symbol into a plurality of interlaces. 
     
     
       28. The computer program product of  claim 27 , in which the program code to decode further comprises program code to decode the plurality of interlaces to determine one of a wide area scrambler seed (WID) value or a local area scrambler seed (LID) value. 
     
     
       29. The computer program product of  claim 21 , in which the program code to determine a channel estimate associated with the transmitter comprise the program code to determine a transmission time associated with the transmitter. 
     
     
       30. The computer program product of  claim 21 , in which the symbol comprises an Orthogonal Frequency Division Multiplexing (OFDM) symbol. 
     
     
       31. An apparatus configured to determine a position of a device in a network, the apparatus comprising:
 a memory unit; and 
 at least one processor coupled to the memory unit; the at least one processor configured:
 to decode a symbol comprising subcarriers to determine identification information that identifies a transmitter, in which the decoding comprises partitioning the subcarriers of the symbol; 
 to determine a channel estimate associated with the transmitter using the subcarriers of the symbol; 
 to repeat the decoding and the determining for a plurality of symbols so that a plurality of transmitters associated with a plurality of channel estimates, respectively, are determined; and 
 to obtain the position of the device based at least in part on positions of the plurality of transmitters. 
 
 
     
     
       32. The apparatus of  claim 31 , in which the at least one processor is further configured to transmit information to a server for calculating a device position based at least in part on the plurality of transmitters and the plurality of channel estimates. 
     
     
       33. The apparatus of  claim 31 , in which the at least one processor is further configured to use triangulation to obtain the device position. 
     
     
       34. The apparatus of  claim 31 , in which the at least one processor is further configured to account for fixed offsets applied by the plurality of transmitters to obtain the device position. 
     
     
       35. The apparatus of  claim 31 , in which the symbol is a positioning pilot symbol. 
     
     
       36. The apparatus of  claim 35 , in which the positioning pilot symbol includes an increased cyclic prefix. 
     
     
       37. The apparatus of  claim 31 , in which the at least one processor is further configured to partition the subcarriers of the symbol into a plurality of interlaces. 
     
     
       38. The apparatus of  claim 37 , in which the at least one processor is further configured to decode the plurality of interlaces to determine one of a wide area scrambler seed (WID) value or a local area scrambler seed (LID) value. 
     
     
       39. The apparatus of  claim 31 , the at least one processor is further configured to determine a transmission time associated with the transmitter. 
     
     
       40. The apparatus of  claim 31 , in which the symbol comprises an Orthogonal Frequency Division Multiplexing (OFDM) symbol.